javascipt: filter introduction and use_javascript skills

javascipt : filter filter

var List = sizes.filter(function (size) {
return size.id == 12;
});

sizes = [
　　{id : 10,,stock:130},{id : 11,stock:120},{id : 12,stock:100}
]

filter is a new array, and then gives it the filtered object, and finally var list it up